Transformer including a rotary or the like movable winding



June 17, 1958 M R A. LE CADRE TRANSFORMER I'NCLIUDING A ROTARY OR THE LI MOVABLE WINDING Filed April 15. 1957 Fig.2 6

INVENTOR MAW/8f iA/mw M600? A E c A 0 85 ATTORNEY justable voltage are known.

TRANSFORMER INCLUDING A ROTARY OR 1 THE LIKE MOVABLE WINDING Maurice Raymond Auguste Le Cadre, Grenoble, France Application April 15, 1957, Serial No. 653,002

Claims priority, application France October 19, 1956 3 Claims. (Cl. 323-47) Transformers operating to produce a gradually ad- Such transformers include at least one movable adjusting winding capable of rotation about its axis and which is constituted by a bare wire wound helically so as to form spaced convolutions over which a brush is adapted to rub, the connection between said movable winding and the stationary winding being ensured by means of a collecting ring provided with a gap and connected with one end of said movable winding and cooperating with a stationary brush connected with the main winding.

My present invention has for its object the provision of a transformer with a gradually adjustable voltage, characterized by the use of a transformer with a rotary or stepped winding associated with a so-called opposition transformer supplying an induced voltage of a direction opposed to the normal voltage of the convolution.

The accompanying diagrammatic drawings illustrate the principle applied to and incorporated in the transformer with a rotary winding embodying my invention.

In the drawings:

Figs. 1 to 3 are theoretical diagrams.

Fig. 4 is a perspective view of the electric connections provided between the rotary windings of the transformer and the winding of the auxiliary transformer termed the opposition transformer.

Fig. 5 shows a magnetic core subdivided into a plurality of elements together with the collecting ring for the rotary windings of the transformer.

It is a well known fact that if a convolution 2, Fig. 1, is positioned around a magnetic core 3 through which a magnetic flux flows, an electromotive force with a voltage U arises in said convolution.

It is also a well-known fact that if, its terminals 4 and 5, Fig. 1, are short-circuited, a high short-cinmit current flows through said convolution, the value of which is limited only by the impedance of the convolution.

In contradistinction, if after a subdivision of the magnetic circuit into two parallel arms 6 and 7 (Fig. 2), the annular convolution is deformed so that it assumes the shape of a figure eight, i. e. so as to form two elementary convolutions 8 and 9 wound in opposite directions and through which pass respectively fluxes of same value and same direction, it will be evident that the electromotive forces induced in each'of the convolutions thus formed are of opposite directions, that the voltage measured across the terminals 11 and 12 is equal to zero and that upon short-circuiting the latter, no passage of current can be detected.

When a convolution 13 (Fig. 3) placed round a single magnetic core 14 through which a flux passes is shortcircuited, it is also possible to prevent any circulation of a current. To this end, the terminals 15 and 16 of the convolution 13 are connected with the terminals 17 and 18 of the secondary winding 19 of an auxiliary socalled opposition transformer 21, the primary winding 22 of which is energized. Obviously, the voltages arising between the terminals 17 and 18 on the one hand and nited States Patent'O the terminals 15 and 16 on the other hand should be exactly equal and of opposite directions. According to my invention, a similar arrangement may be used across the terminals of a collector when it is desired to collect current between a stationary point and a movable point as is the case for transformers to be adjusted under load and provided with rotary windings.

Over the normal magnetic circuit of a main transformer 23 (Fig. 4) are positioned:

A stationary primary winding 24 fed through the mains 25; and

A secondary winding 26 rotating over the core 27. One end of the winding 26 is connected with a point 28 of the open collecting ring 29. Over the bare convolutions of the winding 26, a stationary brush 31 removes a minimum or maximum voltage according to its location.

To allow the passage of current between the terminals 32 and 33 of the secondary winding 26, I resort to the arrangement described hereinafter so as to avoid at any moment the short-circuiting of the collecting ring 29.

, To this end, an auxiliary or opposition transformer 34 hasits magnetic circuit energized by the primary winding 35 fed through a voltage tapped off across the points 36 and 37 of the primary winding 24 of the transformer 23, which winding is fed by the current from the mains 25.

According to a modification, the same result may be obtained by tapping said voltage off a third winding on the transformer 23 (which is not illustrated in the accompanying drawing).

The secondary winding 41 of the opposition transformer 34 is designed so that the voltage arising across its terminals 32 and 33 is equal and opposed to the voltage per convolution of the secondary winding 26 of the main transformer 23. For this purpose the two ends 38 and 39 of the winding 41 are connected with the brushes 42 and 43, which are in contact with the ring 29, through leads 44 and 45 which cross each other, and the medial point 46 of said winding 41 is connected with the output terminal 32.

In the position illustrated in the accompanying diagrammatic drawing, assuming the terminals 33 and 39 of the secondary winding of the opposition transformer are thus connected with the brushes 42 and 43, it is found that no current flows through the secondary winding be cause the electromotive forces are in opposition when the primary winding 35 of said transformer is energized.

it is to be noted that when the secondary winding 26 I of the main transformer rotates, it is possible to increase or decrease the voltage across its terminals 32 and 33. To this end, as soon as it turns in either direction, it is sufficient for one of the brushes 42 or 43 to be in contact with the ring 29 for ensuring continuity of the circuit across the terminals 32 and 33.

From the technical standpoint of its operation, the regulator functions as an ordinary transformer.

It allows an almost continuous adjustment of the value of the voltage since the modifications of the latter which are at a maximum equal to the value of the nominal voltage of aconvolution, may be reduced to one-half, one-quarter, one-eighth or one-sixteenth of the value of the nominal voltage per convolution by a suitable subdivision of the magnetic circuit.

The cross-section of the magnetic core may be subdivided into four elements 46, 47, 48, 49. In this case, the collecting ring may be subdivided into four elements 51, 52, 53, 54 which are interconnected in the manner illustrated in Fig. 5. Between the two contacting brushes 55-56, the value of the voltage is no longer that of the nominal voltage of one convolution but only one-quarter of said nominal value.

It is thus apparent that the sensitivity of adjustment of the voltage to one-half, one-quarter, one-sixth, oneeighth or one-sixteenth of the nominal value of the voltage of the convolution is obtained according as to whether one has subdivided in the same manner the cross-section of the magnetic core. Obviously, the morerthe crosssection of said magnetic core is subdivided the more the power of the opposition transformer may be reduced and the more accurate is the adjustment of the line voltage.

The cost price and the possibilities of adjustment of the transformer with a gradually adjustable voltage used in combination with an opposition transformer allow adapting it to the direct adjustment of the voltage of the utilization circuit.

Possibly, after the passage through the gap of the collecting ring 2?, the energization of the opposition transformer may be automatically cut off by a switch (not illustrated in the drawing) inserted between the terminal 36 and the winding 35 and controlled by the movement of the rotary winding.

Obviously, the invention which relates chiefly to the insertion in a circuit of the secondary of an opposition transformer is not limited 'to the sole case of a transformer with a rotary winding which has been more particularly described hereinabove; it covers in contradistinction all other applications of this opposition transformer, chiefly the case where the latter is used in association with an adjustment transformer of the stepped large power type, the opposition transformer being used instead of the induction coils, resistances or impedances used hitherto.

it will be readily understood that, in all cases, there is provided a parallel crossed connection between the end of the rotary coil 26 and the terminal 32, each of said parallel sections of the circuit including a fraction of the slotted stationary ring 29 extending between the point of engagement of said ring at 28 with the rotary coil 26 and the end of the ring which is connected with the Wire 24 or 45 as the case may be, said wires 44 and 45' leading to a medial tapping 46 on the auxiliary transformer 41, the angular shifting of the coil 26 obviously producing no modifications in the voltages passing through said parallel circuit sections as required for operation since the crossed connection produces a constant reference potential at 28. The second terminal 33 moves in synchronism with the bare rotary coil so as to remain in contacting relationship'therewith on a line parallel with the axis of the coil; the latter may in fact be subdivided into two elementary coils inserted in parallel and cooperating each with a different ring such as 29.

What I claim is:

1. A transformer adapted to produce gradually adjustable voltages comprising a main magnetic circuit including two interconnected elements, an auxiliary magnetic circuit, a primary winding on the first element of the main magnetic circuit, a primary Winding on the auxiliary magnetic circuit, means feeding said primary win-dings with alternating current, a conductive ring slotted to form a transverse gap, surrounding the second,

element of the first magnetic circuit, a revoluble secondary winding mounted on said second element of the first magnetic circuit one end of which slidingly engages the conductive ring, a brush engaging permanently a point of the revoluble secondary winding located along a predetermined generating line thereof, a secondary winding carried by the auxiliary magnetic circuit, a crossed connection between the ends of said secondary winding on the auxiliary magnetic circuit and the terminals of the conductive ring to either side of the gap therein, an output circuit connected across the brush and the medial point of the secondary winding on the second magnetic circuit and means for adjusting the angular setting of the revoluble secondary winding about the first magnetic circuit. t

2. A transformer adapted to produce gradually adjustable voltages comprising a main magnetic circuit including two interconnected elements, an auxiliary magnetic circuit, a primary winding on the first element of the main magnetic circuit, a primary winding on the auxiliary magnetic circuit, means for feeding alternating current to the primary winding on the main magnetic circuit, means for energizing the primary winding on the auxiliary magnetic circuit from a fraction of the primary winding on the main magnetic circuit, a conductive ring slotted to form a transverse gap, surrounding the second element of the first magnetic circuit, .a revoluble secondary winding mounted on said second element of the first magnetic circuit one end of which slidingly engages the conductive ring, a brush engaging permanently a point of the revoluble secondary winding located along a predetermined generating line thereof, a secondarycwinding carried by the auxiliary magnetic circuit, a crossed connection between the ends of said secondary winding on the auxiliary magnetic circuit and the terminals of the conductive ring to either side of the gap therein, an output circuit connected across the brush and the medial point of the secondary winding on the second magnetic circuit and means for adjusting the angular setting of the revoluble secondary winding about the first magnetic circuit.

3. A transformer adapted to produce gradually adjustable voltages comprising a main magnetic circuit including two interconnected elements, the first element of which is solid and the second is subdivided transversely into an even plurality of equal fractions, an auxiliary magnetic circuit, a primary winding on the first element of the main magnetic circuit, a primary winding on the auxiliary magnetic circuit, means feeding said primary windings with alternating current, a conductive ring subdivided into an even plurality of equal independent fractions registering with the corresponding fractions of the second element of the main magnetic circuit, a revoluble secondary winding mounted on said second element of the first magnetic circuit and one end of which slidingly engages the conductive ring, a brush engaging permanently a point of the revoluble secondary winding located along atpredetermi ned generating line thereof, a secondary winding carried by the auxiliary magnetic circuit, a crossed connection between the ends of said secondary winding onthe auxiliary magnetic circuit and odd and even fractions of the slotted ring respectively, an output circuit connected across the brush and the medial point of the secondary winding on the second magnetic circuit and means for adjusting the angular setting of the revoluble winding about the first magnetic circuit.

No references cited. 

